Recently, a standard protocol and a system for wireless Internet service have been actively developed, and accordingly, the importance of a packet transmission technique has been highlighted for pre-empting technical power in a packet-based fourth generation mobile communication system.
A resource allocation request and link packet scheduling methods for satisfying quality of service (QoS) requirements and maximizing wireless link efficiency in packet transmission packet is a specialized field of wireless link sharing, and is valued as an important resource for improving system capacity compared to a conventional wired system.
A resource request includes a series of processes in which user equipment (UE) informs the presence of uplink data to a base station and requests a necessary amount of resource allocation. A scheduling method of which the base station allocates resources to the UE can be divided into an uplink scheduling method and a downlink scheduling method.
According to the downlink scheduling method, the base station allocates resources while checking the amount of data packets stored in a transmit buffer of the base station in real-time. According to the uplink scheduling method, the base station allocates resources on the basis of buffer state information reported from the UE. Therefore, an efficient resource request method is required for maximizing radio resource utilization and providing quality of service (QoS) in the uplink scheduling method. In order to realize the efficient resource request method, a transmit buffer state should be timely reported with sufficient information.
Timeliness indicates that the UE should timely report the transmit buffer state information so as to guarantee QoS. For example, when the amount of data packets queued in the transmit buffer is increasing and the UE does not report the transmit buffer state, data is transmitted through subsequently allocated uplink resources. However, in this case, the resources through which the data is transmitted are allocated without considering the state of the transmit buffer. Therefore, with respect to a network, the data does not satisfy delay requirements. As a result, the data successfully transmitted from a transmitting side may be discarded in a receiving side. Meanwhile, uplink packet scheduling performance may be improved as the number of reports on the state of the transmit buffer of the UE increases. However, excessive resource use may cause a trade-off.
The timeliness of the reporting has a close relationship to a time interval from the time that the UE determines a resource request to the time that the base station perceives the request. As the time that the base station perceives the resource request of the UE is delayed, the time interval is increased, thereby decreasing utility of transmitted data. The delay is closely related to design of frame and channel structures.
Sufficiency of information indicates that information provided by the UE should include sufficient information for efficient uplink scheduling of differentiated multimedia services. For example, in the case of a file transfer protocol (FTP) that is insensitive to time delay compared to other services, information on the amount of packets queued in the transmit buffer is more worthy than information on a packet that has been transmitted to the transmit buffer for the first time (so-called head-of-line, HOL). Therefore, since unnecessary and unimportant information is inappropriate with respect to utilization of radio resources, the reporting contents should include sufficient information for efficient scheduling.
As described, information on the transmit buffer state reported to the base station from the UE for uplink scheduling may be called scheduling information, and the scheduling information must include optimum information for efficient scheduling. The uplink scheduling is performed on the basis of the scheduling information and QoS information exchanged between the UE and the base station when establishing a connection therebetween. The QoS information is an index that should be satisfied on average or ultimately, and the scheduling information is a measure that indicates short-term service satisfaction of a user. Therefore, optimum uplink scheduling can be achieved when the QoS information and the scheduling information are converged to each other. Since the QoS information and the scheduling information vary depending on characteristics of traffic between the UE and the base station, a resource request method and a scheduling method that provide efficient scheduling information according to characteristics of traffic are required in order to achieve optimum uplink scheduling.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.